为什么右键单击会在圆圈中心创建一个橙色点?

Why does the first widget example in kivy lead to an orange circle in the middle of the yellow one when you right click on the canvas and a pure yellow one when you left click?

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.graphics import Color, Ellipse

class MyPaintWidget(Widget):
    def on_touch_down(self, touch):
        with self.canvas:
            Color(1, 1, 0)
            d = 30.
            Ellipse(pos=(touch.x - d/2, touch.y - d/2), size=(d, d))


class MyPaintApp(App):
    def build(self):
        return MyPaintWidget()


if __name__ == '__main__':
    MyPaintApp().run()

解决方案

要禁用多点触控仿真，请在导入任何其他 kivy 模块之前将其添加到包含 main 函数的源文件中:

from kivy.config import Config
Config.set('input', 'mouse', 'mouse,multitouch_on_demand')